diff --git a/kernel/atom.h b/kernel/atom.h
index faa0bdb..a8c2eb3 100755
--- a/kernel/atom.h
+++ b/kernel/atom.h
@@ -31,7 +31,7 @@
 #define __ATOM_H
 
 #include "atomtimer.h"
-#include "atomuser.h"
+#include "atomport.h"
 
 /* Data types */
 
diff --git a/kernel/atomkernel.c b/kernel/atomkernel.c
index ec811f2..02a6260 100755
--- a/kernel/atomkernel.c
+++ b/kernel/atomkernel.c
@@ -146,7 +146,6 @@
 
 #include <stddef.h>
 #include "atom.h"
-#include "atomuser.h"
 
 
 /* Global data */
diff --git a/kernel/atommutex.c b/kernel/atommutex.c
index 8fc616c..cbb6371 100755
--- a/kernel/atommutex.c
+++ b/kernel/atommutex.c
@@ -105,7 +105,6 @@
 #include "atom.h"
 #include "atommutex.h"
 #include "atomtimer.h"
-#include "atomuser.h"
 
 
 /* Local data types */
diff --git a/kernel/atomqueue.c b/kernel/atomqueue.c
index 7b27729..78599f5 100755
--- a/kernel/atomqueue.c
+++ b/kernel/atomqueue.c
@@ -97,7 +97,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtimer.h"
-#include "atomuser.h"
 
 
 /* Local data types */
diff --git a/kernel/atomsem.c b/kernel/atomsem.c
index 3578413..6c5d32d 100755
--- a/kernel/atomsem.c
+++ b/kernel/atomsem.c
@@ -92,7 +92,6 @@
 #include "atom.h"
 #include "atomsem.h"
 #include "atomtimer.h"
-#include "atomuser.h"
 
 
 /* Local data types */
diff --git a/kernel/atomtimer.c b/kernel/atomtimer.c
index f56822d..5376fcb 100755
--- a/kernel/atomtimer.c
+++ b/kernel/atomtimer.c
@@ -69,7 +69,6 @@
 
 #include <stdio.h>
 #include "atom.h"
-#include "atomuser.h"
 
 
 /* Data types */
diff --git a/kernel/atomtimer.h b/kernel/atomtimer.h
index 9e7ccf5..9c182d7 100755
--- a/kernel/atomtimer.h
+++ b/kernel/atomtimer.h
@@ -30,7 +30,8 @@
 #ifndef __ATOM_TIMER_H
 #define __ATOM_TIMER_H
 
-#include "atomuser.h"
+#include "atomport.h"
+
 
 /* Callback function prototype */
 typedef void ( * TIMER_CB_FUNC ) ( POINTER cb_data ) ;
diff --git a/ports/avr/atomport-private.h b/ports/avr/atomport-private.h
new file mode 100644
index 0000000..866f6b4
--- /dev/null
+++ b/ports/avr/atomport-private.h
@@ -0,0 +1,39 @@
+/*
+ * Copyright (c) 2010, Kelvin Lawson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. No personal names or organizations' names associated with the
+ *    Atomthreads project may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE ATOMTHREADS PROJECT AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __ATOM_PORT_PRIVATE_H
+#define __ATOM_PORT_PRIVATE_H
+
+/* CPU Frequency */
+#define AVR_CPU_HZ          1000000
+
+/* Function prototypes */
+void avrInitSystemTickTimer ( void );
+
+#endif /* __ATOM_PORT_PRIVATE_H */
diff --git a/ports/avr/atomuser.h b/ports/avr/atomport-tests.h
similarity index 70%
rename from ports/avr/atomuser.h
rename to ports/avr/atomport-tests.h
index 8f611e0..113cfe2 100644
--- a/ports/avr/atomuser.h
+++ b/ports/avr/atomport-tests.h
@@ -1,59 +1,55 @@
-/*
- * Copyright (c) 2010, Kelvin Lawson. All rights reserved.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- *
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 3. No personal names or organizations' names associated with the
- *    Atomthreads project may be used to endorse or promote products
- *    derived from this software without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE ATOMTHREADS PROJECT AND CONTRIBUTORS
- * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
- * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
- * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE
- * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
- * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
- * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
- * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
- * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
- * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
- * POSSIBILITY OF SUCH DAMAGE.
- */
-
-#ifndef __ATOM_USER_H
-#define __ATOM_USER_H
-
-#include <avr/io.h>
-#include <avr/interrupt.h>
-#include <avr/pgmspace.h>
-
-/* Portable uint8_t and friends available from stdint.h on this platform */
-#include <stdint.h>
-
-
-/* Required number of system ticks per second (normally 100 for 10ms tick) */
-#define SYSTEM_TICKS_PER_SEC            100
-
-
-/**
- * Architecture-specific types.
- * Most of these are available from stdint.h on this platform, which is
- * included above.
- */
-#define POINTER void *
-
-
-/* Critical region protection */
-#define CRITICAL_STORE      uint8_t sreg
-#define CRITICAL_START()    sreg = SREG; cli();
-#define CRITICAL_END()      SREG = sreg
-
-
-#endif /* __ATOM_USER_H */
+/*
+ * Copyright (c) 2010, Kelvin Lawson. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. No personal names or organizations' names associated with the
+ *    Atomthreads project may be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE ATOMTHREADS PROJECT AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
+ * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+ * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef __ATOM_PORT_TESTS_H
+#define __ATOM_PORT_TESTS_H
+
+/* Include Atomthreads kernel API */
+#include "atom.h"
+
+/* Prerequisite include for ATOMLOG() macro (via printf) */
+#include <stdio.h>
+
+/* Logger macro for viewing test results */
+#define ATOMLOG     printf_P
+
+/*
+ * String location macro: for platforms which need to place strings in
+ * alternative locations, e.g. on avr-gcc strings can be placed in
+ * program space, saving SRAM. On most platforms this can expand to
+ * empty.
+ */
+#define _STR(x)     PSTR(x)
+
+/* Default thread stack size (in bytes) */
+#define TEST_THREAD_STACK_SIZE      128
+
+
+#endif /* __ATOM_PORT_TESTS_H */
+
diff --git a/ports/avr/atomport.c b/ports/avr/atomport.c
index 52c6b41..19a1d3c 100644
--- a/ports/avr/atomport.c
+++ b/ports/avr/atomport.c
@@ -31,7 +31,7 @@
 #include <avr/interrupt.h>
 
 #include "atom.h"
-#include "atomport.h"
+#include "atomport-private.h"
 
 
 /** Forward declarations */
diff --git a/ports/avr/atomport.h b/ports/avr/atomport.h
index 426c0a4..89c2793 100644
--- a/ports/avr/atomport.h
+++ b/ports/avr/atomport.h
@@ -30,10 +30,30 @@
 #ifndef __ATOM_PORT_H
 #define __ATOM_PORT_H
 
-/* CPU Frequency */
-#define AVR_CPU_HZ          1000000
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/pgmspace.h>
+
+/* Portable uint8_t and friends available from stdint.h on this platform */
+#include <stdint.h>
+
+
+/* Required number of system ticks per second (normally 100 for 10ms tick) */
+#define SYSTEM_TICKS_PER_SEC            100
+
+
+/**
+ * Architecture-specific types.
+ * Most of these are available from stdint.h on this platform, which is
+ * included above.
+ */
+#define POINTER void *
+
+
+/* Critical region protection */
+#define CRITICAL_STORE      uint8_t sreg
+#define CRITICAL_START()    sreg = SREG; cli();
+#define CRITICAL_END()      SREG = sreg
 
-/* Function prototypes */
-void avrInitSystemTickTimer ( void );
 
 #endif /* __ATOM_PORT_H */
diff --git a/ports/avr/tests-main.c b/ports/avr/tests-main.c
index 13c7876..72e0156 100644
--- a/ports/avr/tests-main.c
+++ b/ports/avr/tests-main.c
@@ -32,7 +32,7 @@
 #include <avr/pgmspace.h>
 
 #include "atom.h"
-#include "atomport.h"
+#include "atomport-private.h"
 #include "atomtests.h"
 #include "atomtimer.h"
 
diff --git a/ports/avr/uart.c b/ports/avr/uart.c
index d6edcb9..036e299 100644
--- a/ports/avr/uart.c
+++ b/ports/avr/uart.c
@@ -18,7 +18,7 @@
 
 #include "atom.h"
 #include "atommutex.h"
-#include "atomport.h"
+#include "atomport-private.h"
 #include "uart.h"
 
 /*
diff --git a/tests/atomtests.h b/tests/atomtests.h
index da28159..9e0d0f2 100644
--- a/tests/atomtests.h
+++ b/tests/atomtests.h
@@ -33,22 +33,9 @@
 /* Include Atomthreads kernel API */
 #include "atom.h"
 
-/* Prerequisite include for ATOMLOG() macro (via printf) */
-#include <stdio.h>
+/* Include port-specific test configuration */
+#include "atomport-tests.h"
 
-/* Logger macro for viewing test results */
-#define ATOMLOG     printf_P
-
-/*
- * String location macro: for platforms which need to place strings in
- * alternative locations, e.g. on avr-gcc strings can be placed in
- * program space, saving SRAM. On most platforms this can expand to
- * empty.
- */
-#define _STR(x)     PSTR(x)
-
-/* Default thread stack size (in bytes) */
-#define TEST_THREAD_STACK_SIZE      128
 
 /* Default thread priority */
 #define TEST_THREAD_PRIO            16
diff --git a/tests/mutex1.c b/tests/mutex1.c
index 6ca9e47..0ad0630 100644
--- a/tests/mutex1.c
+++ b/tests/mutex1.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atommutex.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */
diff --git a/tests/mutex2.c b/tests/mutex2.c
index ab97e2b..e2752ec 100644
--- a/tests/mutex2.c
+++ b/tests/mutex2.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atommutex.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */
diff --git a/tests/mutex8.c b/tests/mutex8.c
index 5ca5745..442d9ff 100644
--- a/tests/mutex8.c
+++ b/tests/mutex8.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atommutex.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */
diff --git a/tests/queue1.c b/tests/queue1.c
index c8ac594..e1f254d 100644
--- a/tests/queue1.c
+++ b/tests/queue1.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/queue10.c b/tests/queue10.c
index 3a5defd..127c27f 100644
--- a/tests/queue10.c
+++ b/tests/queue10.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/queue2.c b/tests/queue2.c
index 9a73f0b..d68a6df 100644
--- a/tests/queue2.c
+++ b/tests/queue2.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/queue3.c b/tests/queue3.c
index 0d2bbae..ec7359b 100644
--- a/tests/queue3.c
+++ b/tests/queue3.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/queue4.c b/tests/queue4.c
index 0ee4233..b584e10 100644
--- a/tests/queue4.c
+++ b/tests/queue4.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /*   Number of queue entries */
diff --git a/tests/queue6.c b/tests/queue6.c
index 64343e2..362a001 100644
--- a/tests/queue6.c
+++ b/tests/queue6.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/queue7.c b/tests/queue7.c
index b06127d..b9f9f4b 100644
--- a/tests/queue7.c
+++ b/tests/queue7.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomqueue.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test queue size */
diff --git a/tests/sem1.c b/tests/sem1.c
index 554d34c..cc1c1d4 100644
--- a/tests/sem1.c
+++ b/tests/sem1.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomsem.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */
diff --git a/tests/sem2.c b/tests/sem2.c
index 7b89e47..925dc53 100644
--- a/tests/sem2.c
+++ b/tests/sem2.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomsem.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */
diff --git a/tests/sem9.c b/tests/sem9.c
index 203033e..141a6c1 100644
--- a/tests/sem9.c
+++ b/tests/sem9.c
@@ -31,7 +31,6 @@
 #include "atom.h"
 #include "atomsem.h"
 #include "atomtests.h"
-#include "atomuser.h"
 
 
 /* Test OS objects */